Tarnish and corrosion behaviour of dental gold alloys

Laub, Leon W.; Stanford, John W.

doi:10.1007/bf03216554

Cited by 20 publications

(14 citation statements)

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“…Dental alloys are considered to exhibit high-level corrosion resistance, but metal ion release in vitro and in vivo has been reported [20][21][22] . It has also been reported that, in gold alloys with a basic composition of Au-AgCu, corrosion occurred in Ag-rich regions followed by Cu-rich regions 23) . Ag-rich and Cu-rich regions may be formed because Ag and Cu do not fuse, promoting local galvanic corrosion 24) .…”

Section: Discussionmentioning

confidence: 91%

Study of corrosion of combinations of titanium/Ti-6Al-4V implants and dental alloys

Yamazoe

2010

Dental Materials Journal

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Metal ions released in 1% lactic acid solution from combinations of titanium fixtures with superstructures made of dental precious metal alloys (dental alloys) and titanium and differences based on the fixing method were investigated. In combinations of titanium with dental alloys, the level of Ti release was influenced by micro-structure of titanium: it was lower when the grain size was smaller. In titanium-titanium combinations, differences in the micro-structure of metal also markedly influenced the dissolution: the level of release increased when the micro-structure of titanium was different. The Ti and V release levels were higher in combination with titanium alloy and titanium than with titanium alloy and dental alloys. Regarding the superstructure-fixture fixing method, the level of Ti release was significantly lower in cement than in direct fixation.

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Section: Discussionmentioning

confidence: 91%

Study of corrosion of combinations of titanium/Ti-6Al-4V implants and dental alloys

Yamazoe

2010

Dental Materials Journal

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“…While tarnish and corrosion are not wholly separate phenornena, past experimental reports have tended to treat them differently (12). Various electrochemical techniques have been applied to study the corrosion ofgold-based alloys.…”

Section: Introductionmentioning

confidence: 99%

Chemical stability of gold dental alloys

Treacy

German

1984

Gold Bull

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The bzocornpatibzlity and desirable working charactei istics ofgold-based alloys are wzdely recognized in dentisti y. Although there has been considerable activity in understanding such characteizstics as hardenability, there is peihaps more significance to the chemical stability ofa dental alloy sznce degradatzon ofa dental alloy duringservzce can inducea toxic response andpromote gingival tissue irritaion.Because of the recognized role of nobility of a dental alloy in determining chemical stability, various compositional specifications have been issued to help ensure successful service. However, it is recognized that alloys meeting these compositional specifications can prove unacceptable in service (1, 2). Conversely there are several alloys in service which appear to perform satisfactorily in spite of an apparently low nobility. These factors serve to illustrate the complex situation which exists concerning acceptance standards for dental alloys; performance standards are regarded as more reliable than compositional standards.This article describes astudy conducted to obtain quantitative tests and data for the tarnish and corrosion behaviour of gold-based dental alloys. The test data necessarily require clinical corroboration to ensure their validity as an indicatorof alloy suitability fororal use. However, significant progress has been made in determining the nature of a minimum, yet comprehensive, test battery. In addition, the procedures described in this report show quantitatively a capability of separating the performances of dental alloys in laboratory tests. Data obtained from five commercial alloys are given to illustrate the application of the testing approach. BackgroundThe chemical instability of dental alloys has long been recognized as a serious problem. Two distinct occurrences may alter the surface condition of a metal in the mouth; corrosion and tarnish. Corrosion involves the electrochemical dissolution of the metal or the formation of reaction products on the surface. Tarnish is the surface discolouration due to the formation of reaction products and is a specific form of corrosion. There have been several previous investigations of both forms ofattack and these have been reviewed by German (3).Because of the more visible nature of tarnish attack, there has been considerable emphasis on this subject in the previous dental alloy studies. Early research in a sulphurized oil bath by Souder and Paffenbarger (4) indicated that 75 weight per cent noble metal in an alloy was necessary to avoid tarnish. Swartz etal. (5) employed 13 different test solutions, using the as-received alloys in an undefined thermal condition, ranked the results in a subjective manner. The general conclusion was that discolouration occurred preferentially in the low nobility alloys when exposed to sulphide solu tions.The study by Tuccillo and Nielsen (6) demonstrated that on a microscopie scale tarnish attack has a galvanic nature. Silver-rich regions were preferentially attacked by the sulphide-containing solution used in...

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“…Laub and Stanford [15] observed a correlation between the composition of five low-carat gold dental alloys and the resultant corrosion and tarnishing results. As the gold content increased from 40 to 59.5 %, a reduction in the electrochemical corrosion rates was observed, in addition to no tarnishing or corrosion from clinical trials being observed for higher gold content alloys.…”

Section: Effect Of Composition On the Corrosion Behaviour Of Gold Alloysmentioning

confidence: 99%

“…Forty [14] has studied the selective dissolution of active constituents in gold alloys and found that selective dissolution is more likely to occur in the lower carat gold alloys. Laub and Stanford [15] reported that for ternary Au-Ag-Cu alloys, both copper and silver were involved in the corrosion process; corrosion occurring primarily in the silver-rich regions and secondarily in the copper-rich regions. Fujita and co-workers [16] observed for an Ag-Au-Pt-Cu alloy, comprising of a mixture of a major phase of the matrix and minor phase of small grains embedded in the matrix, corrosion occurred preferentially in the matrix and not the precipitates.…”

Section: Introductionmentioning

confidence: 99%

The electrochemical corrosion behaviour of quaternary gold alloys when exposed to 3.5 % NaCl solution

2013

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Lower carat gold alloys, specifically 9 carat gold alloys, containing less than 40 % gold, and alloying additions of silver, copper and zinc, are commonly used in many jewellery applications, to offset high costs and poor mechanical properties associated with pure gold. While gold is considered to be chemically inert, the presence of active alloying additions raises concerns about certain forms of corrosion, particularly selective dissolution of these alloys. The purpose of this study was to systematically study the corrosion behaviour of a series of quaternary gold-silvercopper-zinc alloys using dc potentiodynamic scanning in saline (3.5 % NaCl) environment. Full anodic/cathodic scans were conducted to determine the overall corrosion characteristics of the alloy, followed by selective anodic scans and subsequent morphological and compositional analysis of the alloy surface and corroding media to determine the extent of selective dissolution. Varying degrees of selective dissolution and associated corrosion rates were observed after anodic polarisation in 3.5 % NaCl, depending on the alloy composition. The corrosion behaviour of the alloys was determined by the extent of anodic reactions which induce (1) formation of oxide scales on the alloy surface and or (2) dissolution of Zn and Cu species. In general, the improved corrosion characteristics of alloy #3 was attributed to the composition of Zn/Cu in the alloy and thus favourable microstructure promoting the formation of protective oxide/chloride scales and reducing the extent of Cu and Zn dissolution.

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Tarnish and corrosion behaviour of dental gold alloys

Cited by 20 publications

References 14 publications

Study of corrosion of combinations of titanium/Ti-6Al-4V implants and dental alloys

Study of corrosion of combinations of titanium/Ti-6Al-4V implants and dental alloys

Chemical stability of gold dental alloys

The electrochemical corrosion behaviour of quaternary gold alloys when exposed to 3.5 % NaCl solution

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